The invention relates to a disturbance-limiting circuit of redundant type for regulation equipment.
In the field of regulation, it is well known to use a plurality of redundant paths to control a process, e.g. to provide regulated control for a steam turbine, on the basis of a reference value and via a circuit made up of identical regulator modules disposed in parallel.
The resulting control value applied to the process conventionally corresponds to a mean value obtained from the regulated values provided simultaneously by the regulator modules, which modules may be of the proportional and integral type, for example.
In a conventional implementation using analog technology, the control value is a mean voltage value obtained from the voltages respectively delivered by each of the regulator modules, with the voltage outputs from each of them being connected for this purpose to a common point via respective same-value resistances.
In the event of a failure concerning one of the paths, the voltage delivered by the module contained in said path is generally either zero or a maximum, and this gives rise to an unacceptable amount of variation in the applied control value, for example, if the apparatus has three paths this variation may reach 33%.